Question

我通过ItemsSource属性和ItemTemplate属性向TreeView控件添加项目以设置TreeViewItem的模板。如何添加事件处理程序来处理TreeViewItems上的选择更改事件？
现在我的ItemTemplate看起来像这样：

<Window.Resources><DataTemplate x:Key="PeerDetailTemplate">
        <TextBlock Text="{Binding DESCRIPTION}" Tag="{Binding ID}" GotFocus="GetModules"/>
</DataTemplate></Window.Resources>

但它不起作用（不调用GetModules）。我是WPF的新手，请告诉我做这些事情的正确方向。

Answer 1

如果要捕获SelectedItemChanged中的TreeView事件，则需要在父节点上设置事件处理程序，即

<强> XAML

<StackPanel>
    <TreeView SelectedItemChanged="OnTreeViewSelectedItemChanged">          
        <TreeViewItem Header="Desktop">
            <TreeViewItem Header="Computer" />
            <TreeViewItem Header="My Documents" />
            <TreeViewItem Header="c:\" />
        </TreeViewItem>
        <TreeViewItem Header="Recyle Bin" >
            <TreeViewItem Header="foo.txt" />
            <TreeViewItem Header="bar.txt" />
            <TreeViewItem Header="fizz.buzz" />
        </TreeViewItem>
        <TreeViewItem Header="Control Panel" >
            <TreeViewItem Header="Programs" />
            <TreeViewItem Header="Security" />
            <TreeViewItem Header="User Accounts" />
        </TreeViewItem>
    </TreeView>

    <TextBlock Margin="20" x:Name="MyTextBlock" />
</StackPanel>

代码背后：

private void OnTreeViewSelectedItemChanged( object sender, RoutedPropertyChangedEventArgs<object> e )
{
    MyTextBlock.Text = ( (TreeViewItem) ( (TreeView) sender ).SelectedItem ).Header.ToString();
}

Answer 2

您需要向TreeView的SelectedItemChanged事件添加事件处理程序。

<TreeView x:Name="myTreeView"
          SelectedItemChanged="myTreeView_SelectedItemChanged"
          ItemTemplate="{StaticResource PeerDetailTemplate} />

由于在更改选择后触发此操作，您可以使用TreeView的选定项属性来访问树视图项：

private void myTreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        TreeViewItem selectedItem = (TreeViewItem)myTreeView.SelectedItem;
        // do stuff
    }

Answer 3

选择和选择以及焦点是两个不同的概念。听起来你对选择很感兴趣，在这种情况下，它是TreeView的一个属性。事件TreeView.SelectedItemChanged会通知您选择更改，而TreeView.SelectedItem属性会告诉您选择的内容。

Answer 4

有多种方法绑定TreeviewItem的SelectedItemChanged事件：

方法1：直接附加事件

事件的附件可以在Xaml中完成

<TreeView x:Name="treeview1" HorizontalAlignment="Left" Height="243" Margin="30,211,0,0" VerticalAlignment="Top" Width="667" SelectedItemChanged="TreeView_SelectedItemChanged">
        <TreeViewItem Header="TreeViewItem"/>
</TreeView>
Private void TreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{

}

或者在后面的代码上

myTreeview.SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(TreeView_SelectedItemChanged);

private void TreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{

}

方法2扩展类的用法

public class ExtendedTreeView : TreeView
{
    public ExtendedTreeView()
        : base()
    {
        this.SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(TreeView_SelectedItemChanged);
    }

    void TreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        if (SelectedItem != null)
        {
            SetValue(SelectedItem_Property, SelectedItem);
        }
    }

    public object SelectedItem_
    {
        get { return (object)GetValue(SelectedItem_Property); }
        set { SetValue(SelectedItem_Property, value); }
    }
    public static readonly DependencyProperty SelectedItem_Property = DependencyProperty.Register("SelectedItem_", typeof(object), typeof(ExtendedTreeView), new UIPropertyMetadata(null));
}

接下来，只需使用新的自定义类对象创建Treeview。

ExtendedTreeView  myTreeview = new ExtendedTreeView();

方法3行为的用法

public class BindableSelectedItemBehavior : Behavior<TreeView>
{
    #region SelectedItem Property

    public object SelectedItem
    {
        get { return (object)GetValue(SelectedItemProperty); }
        set { SetValue(SelectedItemProperty, value); }
    }

    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register("SelectedItem", typeof(object), typeof(BindableSelectedItemBehavior), new UIPropertyMetadata(null, OnSelectedItemChanged));

    private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var item = e.NewValue as TreeViewItem;
        if (item != null)
        {
            item.SetValue(TreeViewItem.IsSelectedProperty, true);
        }
    }

    #endregion

    protected override void OnAttached()
    {
        base.OnAttached();

        this.AssociatedObject.SelectedItemChanged += OnTreeViewSelectedItemChanged;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.SelectedItemChanged -= OnTreeViewSelectedItemChanged;
        }
    }

接下来，只需将Treeview附加到Behavior 在Xaml文件上

<TreeView>
    <e:Interaction.Behaviors>
        <behaviours:BindableSelectedItemBehavior SelectedItem="{Binding SelectedItem, Mode=TwoWay}" />
    </e:Interaction.Behaviors>
</TreeView>

或者在后面的代码上

BindableSelectedItemBehavior selectedItemBehavior = new BindableSelectedItemBehavior();
System.Windows.Interactivity.Interaction.GetBehaviors(treeview1).Add(selectedItemBehavior);

私下

在WPF中为TreeViewItem创建事件处理程序

4 个答案: